The idea of “wearable computers” and electronic circuits built entirely out of textiles to distribute data and power and designed to perform functions such as touch sensing was first fully described in a disclosure called “Smart Fabric, or Washable Computing” by E. Rehmi Post and Maggie Orth of the MIT Media Laboratory available on the Internet at http:/www.media.mit.edu/%7EREHMI/fabric/index.html and also on pp. 167-168 of the Digest of Papers of the First IEEE International Symposium on Wearable Computers, Oct. 13-14, 1997 held in Cambridge, Mass.
Prior to the applicant's invention described herein, electrical or electronic components were sometimes fastened to articles of clothing or placed in pouches or pockets. Individual wires between these components were then fastened to the outside of the clothing or disposed partially or wholly in seams and the like. In this way, a soldier could “wear” a radio and a computer and/or global positioning satellite system. Consumers, in turn, could, for example, “wear” a cellular telephone connected to a headset or a speaker and/or microphone located on the collar of a jacket.
The problem with this design is that the wires are separate from the textile material of the clothing. As a result, the wires are unsightly and uncomfortable, do not wear well, can catch and tangle on objects, reduce mobility, add weight, are not washable, and are not resistant to corrosion. In general, such a design is not very robust.
Therefore, those skilled in the art sought to integrate the electronic circuits and data and power conductors within the textile of the articles of clothing themselves. See the MIT disclosure referred to above and incorporated herein by this reference. In the MIT reference, metallic yarn forms the weft of the fabric and, running in the other direction, plain silk thread forms the warp of the fabric. Surface mount light emitting diodes (LED's), crystal piezo transducers, and other surface mount components are then soldered directly onto the metallic yarn.
But, since the metallic yarn only runs in one direction, communications and interconnections between the electronic devices can only take place in that direction. Worse, the individual metallic yarns which do not electrically interconnect two components must be cut to provide electrical isolation for the individual metallic yarns which do electrically interconnect two components. This design thus raises serious design concerns, namely manufacturability, shielding, and electrical interference. Moreover, the fabric including the soldered-on electronic components is delicate, cannot be washed, has no stretch, and is uncomfortable to wear. Finally, if the fabric is folded back on itself, an electrical short will occur. Thus, special insulative coatings or substrates must be used which further render the fabric uncomfortable to wear.
Others have designed textile fabrics with conductive fibers for electrically interconnecting two electronic components. See U.S. Pat. Nos. 6,080,690 and 5,906,004 incorporated herein by this reference. Again, the main idea is that the whole garment is made of this special fabric. As such, a sensor can be electrically connected to a controller right on the garment. Still, routing of the data or power between the devices is limited without extensive formation of electrical junctions in the fabric—a very cumbersome manufacturing process. In addition, such garments are also uncomfortable and cannot withstand repeated wash cycles. See also U.S. Pat. No. 3,414,666 incorporated herein by this reference.
Commonly owned U.S. Pat. No. 6,727,197, incorporated herein by this reference, discloses designs of textile materials with integrated data or power buses which are simple to manufacture, pleasing in appearance, comfortable, washable, which wear well, which do not add significant weight, which are corrosion resistant, which do not impede mobility, which exhibit high fatigue strengths, and which also properly meet or exceed the electrical interface and shielding requirements of the specific application, be it military or consumer-based.
The present invention more particularly relates to physiological sensing systems as they pertain to wearable electronics. Such systems (e.g., garments) are useful for ambulatory/home monitoring (prophylaxis, diagnosis and/or treatment), in-hospital post-operative monitoring, athletic performance training, infant respiration monitoring for the detection of sudden infant death syndrome, and the like. There has been a lot of activity in this field and in one example it is proposed to include conductive electrocardiogram electrodes and inductive plethysmographic sensors sewn, embroidered, embedded or otherwise attached to a garment such as a shirt with an adhesive. See, for example, U.S. Pat. No. 6,047,203 incorporated herein by this reference.
To date, however, the applicants are unaware of a marketable system which employs low profile sensors held in position against the body throughout a typical range of movements for mechanical and electrical coupling. And, although the prior art teaches garments with integral electrodes and sensors, there is a general failure in the art to consider a non-intrusive, conformable, comfortable integrated data/power bus for providing power to the sensors and electrodes (as required) and for routing sensor/electrode signals to the appropriate processing and/or transmission circuitry.
Any viable system will probably be required to include physiological sensors, electrodes, a textile data/power bus with the appropriate connectors and conductors, sensor conditioning/processing capability, and a power source. Optional elements could be body worn or externally located for analysis and warning features and also include a communication system to support data transmission. A preferred system would include a textile-based elastic body conforming garment including textile fibers formed using knitting, weaving, or braiding techniques and incorporating elastic fiber elements such as Lycra. The sensors would include one or more physiological sensors such as ECG or R-wave sensors, EMG sensors, a respiration sensor, and perhaps skin temperature and body position and motion sensors. Preferably, the sensors would be integral to the garment and operate without the requirement of any user manipulation. Gels and adhesives would preferably not be required. The sensors and their associated electronics should be modular and detachable from the garment for replacement or maintenance. The data/power bus should also be integrated into the garment textile structure to minimize intrusiveness and to maximize user comfort and convenience. The data/power bus should also be transparent to the user and require minimal user manipulation after the system has been donned. The garment should be moisture and temperature resistant for operation under typical environmental conditions, and could include a combination of reusable washable elements and, in some examples, disposable elements. Integral connectors would allow the sensors and electronics to be detached for washing and the remaining garment should survive numerous wash cycles. In another possibility, the sensors and electronics of the system are permanently attached to the garment if it can be manufactured at such a cost that it can be disposed of.
A review of the prior art reveals no system which meets the above criteria for a viable physiological monitoring garment.